The art of glass-making contributed in such a degree to the wealth of Venice that glass-makers were regarded as benefactors of the State, and all the glass-makers of Murano were inscribed from their birth in the class of citizens ‘de jure.’ Another very wise measure of the Venetian government with regard to this intermediate class between the aristocracy and the people was the concession of its privileges to foreign persons of respectable origin established in Venice. It was only in the middle of the fourteenth century that citizenship ‘by grace’ was regularly admitted, and it was of two kinds: the one ‘de intus,’ and the other ‘de intus et de extra.’ The first conferred only a certain number of privileges, as that of engaging in commerce, and of holding some office of secondary importance in the public administration; the second conferred the full privileges enjoyed by the citizens ‘de jure,’ including those of sending vessels to sea under the flag of Saint Mark, and of carrying on business in the cities and ports where Venetian commerce was established, with the full rights of a Venetian. Although it was only in 1450 that the law regularised the admission to citizenship, a number of admissions took place before the time of the foundation of the caste. [Sidenote: _Molmenti, Vita Privata, 48._] The miserable conditions of navigation in the fourteenth century, and the depredations of pirates, caused many to request the privilege of navigating under the protection of the Venetian Republic. Those who asked this were generally noble and rich persons. For instance, in 1301 we find the favour asked by the Scrovegni of Padua, by Azzone, Marquis of Este and Ancona, in 1304 by the lords of Camino, mentioned by Dante, by Ludovico Gonzaga, lord of Mantua, and many others. Venice not infrequently offered the title of citizen, with all rights belonging to it, to persons who had exhibited special marks of talent in other parts of Italy; it was offered to Messer Ravagnino, a student of physical science in Belluno, and to Petrarch. It was frequently given to foreigners who had lived as long as twenty-five years in the city, and to others who had voluntarily submitted during a certain number of years to standing guard, paying taxes, and the like; and further, to those who, having married Venetian women of the citizen class, desired to fix their residence in the island of Rialto. Among the foreigners who were thus generally adopted, some of the most interesting in the fourteenth century were the inhabitants of Lucca, who between 1310 and 1340 fled before the tyranny of Castruccio Castracane. These were about thirty families, almost all of which had been in their own country spinners and weavers of silk, and they had brought a numerous retinue of weavers and spinners with them. The Venetians at once understood the advantage to be derived from this immigration of an [Sidenote: _Galliccioli, ii. 274._]